| Scytosiphon lomentaria (Lyngbye.) Link which attachs to Phaeophyta, Phaeosporeae, Scytosiphonaceae, Scytosiphon, is widely distributed from Baltic Sea to the coast of Austrilia and Chile, and usually grows on bedrocks, stones of mid and low-tide zone. Its distribution in China includes the coastal areas from Liaodong Peninsula in the north to Hailing Island of Guangdong Province in the south. S. lomentaria has a life cycle of alternation of heteromorphic generation, which is composed of macroscopic erect gametophytes and microscopic sporophytes. The gametophytes of S. lomentaria are cylindrical-formed mature thalli, presenting tawny to dark brown, which can grow up to 15-70cm long and 2-5mm in diameter.The sporophytes are characterized by three alternative forms, including filaments, crustose and cushion-like thalli, among which filaments are the optimal object for germplasm preservation for their stable biological properties and high speed of amplificationS. lomentaria is a kind of superior sea vegetable with delicious taste and high nutritional value, which is very popular among coastal residents in China, Japan and Korea. Besides, S. lomentaria performs high medical value that attributes to its high activity in antioxidant, antitumor, antivirus and antibacterial aspects. Furthermore, as a kind of macroalgae, S. lomentaria also plays an important role in the ecological restoration, antifouling and removing the excess nutrient elements in seawater. In conclusion, S. lomentaria is an emerging alga possessing high quality as well as promising perspective.The amplification of filaments, sporangia induction and spore collecting are known as basic steps in S. lomentaria culture, among which the rapid amplification of filaments is the key techniques. Nevertheless, once out of control,the contamination of unwanted-alga during the amplification of filaments can lead to a failure in S. lomentaria culture.Chroococcus turgidus which attachs to Cyanophyta, is a common alga that contaminates the filaments of S. lomentaria in the amplification culture. C. turgidus is a kind of prokaryote with rapid speed of amplification and high competitiveness. Owning to these features, C. turgidus can affect the growth and development of filaments of S. lomentaria and even give rise to destruction of the breeding of filaments of S. lomentaria. In this paper, on basis of realizing the biological features of C. turgidus, a co-cultured system of filaments of S. lomentaria and C. turgidus was constructed to study the effects of environmental factors as well as five common antibiotics on the growth of both algae. This paper aims to explore the effects of contamination of C. turgidus on the growth of filaments of S. lomentaria, and efficient methods to inhibit and eliminate C. turgidus, so that we can lower the risk of contamination of C. turgidus in the germplasm preservation, and provide guarantee for the amplification of filaments of S. lomentaria.The results were as follows:1. C. turgidus had a strong adaptiveness to light intensity, photoperiod, temperature and concentration of N and P. (1) Low light intensity [14.4μmol/(m2·s)] showed inhibition on the growth of C. turgidus, while [43.2-100.8μmol/(m2·s)] was the appropriate range of light intensity for C. turgidus. (2) Photoperiod had less influence on the growth of C. turgidus, and 14D:10L was the optimal photoperiod for the growth of C. turgidus. (3) There was a positive correlation between the daily average growth rates of C. turgidus and temperature in the range of 4.0-24.0℃, and the appropriate temperature range was 16.0-24.0 ℃. (4) The optimal concentration of N (NaNO3) was 50.0mg/L, the daily average growth rate of C. turgidus was only 1.32% at the concentration of 1.0mg/L. (5) The appropriate range of concentration of P (NaH2PO4) was 5.0-10.0 mg/L, low concentration (0.1 mg/L) showed evident inhibition on the growth of C. turgidus by reducing its daily average growth rate to 4.09%.2. In the co-cultured system, C. turgidus showed stronger adaptiveness to the environment than filaments of S. lomentaria and held advantages consistently. (1) C. turgidus had broader range of light intensity than S. lomentaria. The growth of filaments of S. lomentaria was inhibited by both low [14.4μmol/(m2·s)] and high [129.6μmol/(m2s)] light intensity, while the growth of C. turgidus was only restrained by low light intensity [14.4μmol/(m2·s)]. (2) Photoperiod showed less influence on both algae. Filaments of S. lomentaria were suppressed under the condition of 8L:16D, but the daily average growth rates of C. turgidus kept over 14.00% all along. (3) Growth of filaments of S. lomentaria was inhibited by both low (8.0℃) and high (24.0℃) temperature in the co-cultured system while C. turgidus was not affected. And there was a positive correlation between the daily average growth rates of C. turgidus and temperature in the range of 8.0-24.0℃. (4) Both algae were restrained by low concentration of N (NaNO3) (30.0 mg/L) under the co-cultured condition, in which case filaments of 5. lomentaria grew worse. (5) Growth of C. turgidus was suppressed at low concentrations of P (NaH2PO4) (1.0 mg/L,2.0mg/L), meanwhile, growth of S. lomentaria was also inhibited significantly.3. Growth of both algae benefited from red light, in which the color of C. turgidus turned dark green for the increasing of chlorophyll and phycobiliprotein possibly. (2) Daily average growth rate of C. turgidus was reduced by blue light, while filaments of S. lomentaria were also inhibited. (3) Both algae were distinctly supressed by green light, in which case both daily growth rates and cells’states were poor.4. (1) Str inhibited the growth of C. turgidus significantly at the concentration of 100 μg/mL, while filaments of S. lomentaria were not affected; (2) Amp and Gm had obvious inhibitory effects on the growth of C. turgidus at the concentration of 100μg/mL, and filaments of S. lomentaria were inhibited at concentrations of 100μg/mL and 500μg/mL respectively; (3) The growth of the filaments of 5. lomentaria was not suppressed by Km within the setting range of concentration in this research, while 100μg/mL Km inhibited C. turgidus intensively; (4) Both filaments of S. lomentaria and C. turgidus were particularly sensitive to Cm, the growth of C. turgidus was inhibited by 10μg/mL Cm distinctly and filaments of S. lomentaria were also suppressed when the concentration of Cm reach 10μg/mL. The results mentioned above revealed that Str (100μg/mL), Km (100-200μg/mL) and Cm (10μg/mL) could be applied to reduce the risk of contamination of C. turgidus during the preservation and amplification of filaments of S. lomentaria. |
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